The Duke of Cornwall is described by Shakespeare as the cruel spouse of Regan. The dominant features of his character are anger, frenzy and fanatical ambition. He is prone to cunning and duplicity, which is clearly manifested in the episode with a greeting from Edmund. Cornwall decides to harbor his hatred and at the appropriate moment bring it down on the enemy. The Duke does not believe in the honesty of other people, attributing to them own falsity. Sometimes he is unable to control his vices. Then, before us appears not a civilized European, but a barbarian, able to wrest his opponent's eyes and trample them with his own boot. In the image of Cornwall incarnate all-consuming human hate, not recognizing good and mercy.
Duke of Cornwall in the Essays